## Two-mode PLC-based mode multi/demultiplexer for mode and wavelength division multiplexed transmission |

Optics Express, Vol. 21, Issue 22, pp. 25752-25760 (2013)

http://dx.doi.org/10.1364/OE.21.025752

Acrobat PDF (1159 KB)

### Abstract

We proposed a PLC-based mode multi/demultiplexer (MUX/DEMUX) with an asymmetric parallel waveguide for mode division multiplexed (MDM) transmission. The mode MUX/DEMUX including a mode conversion function with an asymmetric parallel waveguide can be realized by matching the effective indices of the LP_{01} and LP_{11} modes of two waveguides. We report the design of a mode MUX/DEMUX that can support C-band WDM-MDM transmission. The fabricated mode MUX/DEMUX realized a low insertion loss of less than 1.3 dB and high a mode extinction ratio that exceeded 15 dB. We used the fabricated mode MUX/DEMUX to achieve a successful 2 mode x 4 wavelength x 10 Gbps transmission over a 9 km two-mode fiber with a penalty of less than 1 dB.

© 2013 Optical Society of America

## 1. Introduction

2. T. Morioka, Y. Awaji, R. Ryf, P. Winzer, D. Richardson, and F. Poletti, “Enhancing optical communications with brand new fibers,” IEEE Commun. Mag. **50**(2), s31–s42 (2012). [CrossRef]

3. K. Imamura, Y. Tsuchida, K. Mukasa, R. Sugizaki, K. Saitoh, and M. Koshiba, “Investigation on multi-core fibers with large Aeff and low micro bending loss,” Opt. Express **19**(11), 10595–10603 (2011). [CrossRef] [PubMed]

6. K. Saitoh, M. Koshiba, K. Takenaga, and S. Matsuo, “Crosstalk and core density in uncoupled multicore fibers,” IEEE Photon. Technol. Lett. **24**(21), 1898–1901 (2012). [CrossRef]

7. H. Takara, A. Sano, T. Kobayashi, H. Kubota, H. Kawakami, A. Matsuura, Y. Miyamoto, Y. Abe, H. Ono, K. Shikama, Y. Goto, K. Tsujikawa, Y. Sasaki, I. Ishida, K. Takenaga, S. Matsuo, K. Saitoh, M. Koshiba, and T. Morioka, “1.01-Pb/s(12 SDM/222 WDM/456 Gb/s) crosstalk-managed transmission with 91.4-b/s/Hz aggregate spectral efficiency,” ECOC2012, paper Th.3.C.1 (2012).

8. V. A. J. M. Sleiffer, Y. Jung, V. Veljanovski, R. G. H. van Uden, M. Kuschnerov, H. Chen, B. Inan, L. G. Nielsen, Y. Sun, D. J. Richardson, S. U. Alam, F. Poletti, J. K. Sahu, A. Dhar, A. M. J. Koonen, B. Corbett, R. Winfield, A. D. Ellis, and H. de Waardt, “73.7 Tb/s (96 x 3 x 256-Gb/s) mode-division-multiplexed DP-16QAM transmission with inline MM-EDFA,” Opt. Express **20**(26), B428–B438 (2012). [CrossRef] [PubMed]

9. E. Ip, N. Bai, Y. K. Huang, E. Mateo, F. Yaman, M. J. Li, S. Bickham, S. Ten, J. Liñares, C. Montero, V. Moreno, X. Prieto, V. Tse, K. M. Chung, A. Lau, H. Y. Tam, C. Lu, Y. Luo, G. D. Peng, and G. Li, “88×3×112-Gb/s WDM transmission over 50 km of three-mode fiber with inline few-mode fiber amplifier,” ECOC2011, paper Th.13.C.2 (2011).

8. V. A. J. M. Sleiffer, Y. Jung, V. Veljanovski, R. G. H. van Uden, M. Kuschnerov, H. Chen, B. Inan, L. G. Nielsen, Y. Sun, D. J. Richardson, S. U. Alam, F. Poletti, J. K. Sahu, A. Dhar, A. M. J. Koonen, B. Corbett, R. Winfield, A. D. Ellis, and H. de Waardt, “73.7 Tb/s (96 x 3 x 256-Gb/s) mode-division-multiplexed DP-16QAM transmission with inline MM-EDFA,” Opt. Express **20**(26), B428–B438 (2012). [CrossRef] [PubMed]

9. E. Ip, N. Bai, Y. K. Huang, E. Mateo, F. Yaman, M. J. Li, S. Bickham, S. Ten, J. Liñares, C. Montero, V. Moreno, X. Prieto, V. Tse, K. M. Chung, A. Lau, H. Y. Tam, C. Lu, Y. Luo, G. D. Peng, and G. Li, “88×3×112-Gb/s WDM transmission over 50 km of three-mode fiber with inline few-mode fiber amplifier,” ECOC2011, paper Th.13.C.2 (2011).

16. R. Ryf, M. A. Mestre, A. H. Gnauck, S. Randel, C. Schmidt, R.-J. Essiambre, P. J. Winzer, R. Delbue, P. Pupalaikis, A. Sureka, Y. Sun, X. Jiang, D. W. Peckham, A. McCurdy, and R. Lingle, Jr., “Low-loss mode coupler for mode-multiplexed transmission in few-mode fiber,” OFC2012, paper PDP5B.5 (2012).

21. H. Kubota, M. Oguma, and H. Takara, “Three-mode multi/demultiplexing experiment using PLC mode multiplexer and its application to 2+1 mode bi-directional optical communication,” IEICE Electron. Express **10**(12), 1–6 (2013). [CrossRef]

_{01}and LP

_{11}modes of two waveguides. We investigated the relationship between the LP

_{01}to LP

_{11}mode coupling ratio and the bandwidth as regards the waveguide parameters of the AMC. We then fabricated an AMC supporting C-band MDM-WDM transmission, which realized a low insertion loss of less than 1.3 dB and a high mode extinction ratio of more than 15 dB. Finally, we achieved an MDM-WDM transmission in the C-band over a 9 km-long two-mode fiber with a low power penalty of less than 1 dB by using the fabricated AMC.

## 2. Mode multi/demultiplexing with asymmetric mode coupler

_{01}mode from port 2 is converted to the LP

_{11}mode in waveguide 1 and output at port 3, and the LP

_{01}mode from port 1 is output directly at port 3. Thus, the LP

_{01}and LP

_{11}modes are multiplexed at port3. The AMC can also be used as a mode DEMUX because the coupler has a symmetric property. Since the input or output signals at a MUX/DEMUX are propagated as the fundamental mode when we use this AMC, we can construct an MDM transmission system with conventional single-mode optical devices in transmitters and receivers.

_{01}and LP

_{11}modes needs to match the effective index of the LP

_{11}mode in waveguide 1 to that of the LP

_{01}mode in waveguide 2 as shown in Fig. 2(a) [20]. The effective indices of the LP

_{01}and LP

_{11}modes increase with the waveguide width when the relative refractive index difference (Δ) is constant. Thus, the LP

_{01}mode in waveguide 2 can be coupled to the LP

_{11}mode in waveguide 1 by increasing w1 appropriately compared with w2 as shown in Fig. 2(a). Figure 2(b) shows the waveguide width dependence of the effective indices of the LP

_{01}and LP

_{11}modes at a wavelength of 1550 nm. Here, we assumed that Δ was 0.4% and the waveguide height and width were the same. Since single-mode operation can be realized with a waveguide width smaller than 7.5 μm over the S – L bands with this Δ, we selected a w2 value of 7.5 μm. To match the effective indices of the LP

_{11}and LP

_{01}modes, the w1 and w2 values were required to be 19.3 and 7.5 μm, respectively. So the mode multi/demultiplexing of the LP

_{01}and LP

_{11}modes can be realized with an appropriate L on a certain G for these waveguide widths.

_{01}and LP

_{11}modes. The solid and dashed lines show waveguide widths w1 and w2, respectively. w2 was set at the maximum value for single-mode operation at a wavelength of 1450 nm when we assumed a square waveguide structure. w1 was about 2.6 times as wide as w2 with the same height as shown Fig. 3(a). We then calculated the interaction length as the peak coupling ratio of the LP

_{11}mode at a wavelength of 1550 nm for each Δ when we set the gaps at 2.0 and 3.0 μm, respectively. The solid and dashed lines show the interaction length in gaps for 2.0 and 3.0 μm, respectively. The interaction length became long as the waveguide gap increased as shown in Fig. 3(b). Moreover, the interaction length remained constant with increasing Δ.

_{11}a and LP

_{11}b), we assumed the use of only the LP

_{11}a mode in this design. Figure 4 shows the interaction length calculated as a function of G. Here, L was calculated as the peak coupling ratio of the LP

_{11}mode at a wavelength of 1550 nm. L was roughly proportional to G. When we set G values of 3.0 and 4.0 μm, the L values were 2.21 and 3.31 mm, respectively. Figures 5(a) and 5(b) show the wavelength dependence of the coupling ratio to port 3 from ports 1 and 2 as a function of wavelength for G values of 3.0 and 4.0 μm, respectively. The solid, dashed and dotted lines show the coupling ratios of the LP

_{01}, LP

_{11}x, and LP

_{11}y modes, respectively. Here, the coupling ratio of the LP

_{01}mode indicated the x-polarized value because the coupling ratios of the x and y polarizations in the LP

_{01}mode were almost the same. The coupling ratio of the LP

_{01}mode was higher than 98% at gaps of 3.0 and 4.0 μm between 1450 ~1650 nm. The coupling ratios of the LP

_{01}and LP

_{11}modes were higher than 98% at gaps of 3.0 and 4.0 μm in the entire C-band. Moreover, we consider that this AMC could be used in an MDM system with polarization division multiplexing because of its low polarization dependence.

_{11}mode. Here, the coupling ratio of the LP

_{01}mode was almost 100% at a gap of more than 4.0 μm. There were relatively large changes in the coupling ratio and bandwidth with gaps between 2.0 and 3.0 μm. Then the coupling ratio increased monotonously with gaps between 3.0 and 6.0 μm. In contrast, the bandwidth decreased as the waveguide gap increased. So the peak coupling ratio and bandwidth had a tradeoff relation, and these values were polarization insensitive. Therefore, we assumed that a relatively high coupling ratio and wide bandwidth can be realized by adopting a gap of between 3.0 and 4.0 μm in the AMC.

## 3. Property of fabricated AMC

_{01}mode pattern was observed at port 3 when input into port 1. The LP

_{11}mode pattern was clearly observed by converting the LP

_{01}mode from port 2 to the LP

_{11}mode in the waveguides. We also observed a mixed electric field consisting of the LP

_{01}and LP

_{11}modes when CW light was input into both ports. We also observed similar field patterns for AMC2 as shown in the second row of Fig. 7. Thus the fabricated AMCs successfully performed as a mode multiplexer for the LP

_{01}and LP

_{11}modes.

_{01}and LP

_{11}modes between 1500 and 1620 nm. Figures 8(a) and 8(b) show the insertion losses of AMC1 and AMC2, respectively. The open and filled circles are the insertion losses of the LP

_{01}and LP

_{11}modes, respectively. The insertion loss of the fabricated AMCs had a low wavelength dependence and the insertion losses of AMC1 and AMC2 were less than 0.8 and 1.3 dB, respectively. We considered the insertion loss of AMC2 to be larger than that of AMC1 because with AMC2 there was a misalignment between the waveguide and the splicing fiber. We realized a low insertion loss with a low mode dependence. Since the primary factor as regards the insertion loss was the mode field diameter (MFD) mismatch between the waveguide and the splicing fiber, we believe that the insertion loss can be improved by reducing the MFD mismatch.

_{11}to LP

_{01}and LP

_{01}to LP

_{11}mode extinction ratios, respectively. Additionally, the solid and dashed lines are the calculated LP

_{01}to LP

_{11}and LP

_{11}to LP

_{01}mode extinction ratios, respectively. We confirmed that the calculated result agreed relatively well with the measured result. The LP

_{01}to LP

_{11}mode extinction ratio exceeded 20 dB between 1500 and 1620 nm in both fabricated AMCs. Furthermore, the LP

_{11}to LP

_{01}mode extinction ratio exceeded 15 dB over the C-band. Therefore, we were able to realize a mode MUX/DEMUX with a low insertion loss and a relatively high mode extinction ratio. In the future, we believe that a higher mode extinction ratio and wider bandwidth will be realized by employing the WINC structure [19].

## 4. Mode division multiplexed transmission with fabricated AMC

_{11}mode of longer than 1600 nm. The MFD and the transmission loss of the LP

_{01}mode were 11.69 μm and 0.2 dB/km, respectively, at a wavelength of 1550 nm. The light sources were DFB-LDs operating at 1534, 1542, 1552, and 1557 nm. These lights were modulated at 10 Gbps in a non-return-to-zero modulation format with a 2

^{31}−1 pseudorandom binary sequence (PRBS) by using a lithium niobate (LN) intensity modulator. The optical signals were divided into two with a 3 dB power coupler and guided into ports 1 and 2, respectively in the mode MUX. Signals at port 1 were guided into a transmission medium in the LP

_{01}mode via the designed mode MUX. In contrast, the signals at port 2 were multiplexed in the LP

_{11}mode in the transmission medium after the LP

_{01}modes had been converted to LP

_{11}modes in the mode MUX. These transmitted MDM-WDM signals were demultiplexed with a mode DEMUX, which had the same structure as the mode MUX, and were then demultiplexed to each wavelength with an AWG. After that each channel was amplified with an erbium-doped fiber amplifier (EDFA). Figures 11(a) and 11(b), respectively, show the BER characteristics as a function of the received power of the LP

_{01}and LP

_{11}modes with AMC1. Figures 11(c) and 11(d), respectively, show the BERs of the LP

_{01}and LP

_{11}modes with AMC2. The solid and dashed lines show the BERs for back-to-back and 9 km transmissions, respectively. We confirmed that the LP

_{01}and LP

_{11}modes were successfully transmitted without any noticeable error floor.

_{01}mode transmission was larger than that for the LP

_{11}mode with AMC1 as shown in Figs. 11(a) and 11(b). We assumed that this penalty was generated by the LP

_{11}b mode crosstalk. The LP

_{11}b mode was insufficiently suppressed because of the short interaction length in AMC1. The LP

_{01}and LP

_{11}modes were successfully transmitted with a power penalty of less than 1 dB by using AMC2, which has a longer interaction length than AMC1. Although the LP

_{11}b mode suppression was effective in increasing the interaction length, a long interaction length had a reduced bandwidth as shown in Fig. 6. Therefore, when designing an AMC we must consider the coupling ratio, bandwidth and suppression of unnecessary modes in order to satisfy the MDM transmission characteristics. Our results show that the PLC-based mode MUX/DEMUX can contribute to MDM-WDM transmission.

## 5. Conclusion

_{01}and LP

_{11}modes. A 2 mode x 4 wavelength x 10 Gbps MDM-WDM transmission was successfully realized over a 9 km-long two-mode fiber in the C-band with a low-power penalty.

## Acknowledgments

## References and links

1. | D. Qian, M. F. Huang, E. Ip, Y. K. Huang, Y. Shao, J. Hu, and T. Wang, “101.7-Tb/s (370x294-Gb/s) PDM-128QAM-OFDM transmission over 3x55-km SSMF using pilot-based phase noise mitigation,” OFC2011, paper PDPB5 (2011). |

2. | T. Morioka, Y. Awaji, R. Ryf, P. Winzer, D. Richardson, and F. Poletti, “Enhancing optical communications with brand new fibers,” IEEE Commun. Mag. |

3. | K. Imamura, Y. Tsuchida, K. Mukasa, R. Sugizaki, K. Saitoh, and M. Koshiba, “Investigation on multi-core fibers with large Aeff and low micro bending loss,” Opt. Express |

4. | T. Hayashi, T. Taru, O. Shimakawa, T. Sasaki, and E. Sasaoka, “Characterization of crosstalk in ultra-low-crosstalk multi-core fiber,” J. Lightwave Technol. |

5. | M. Koshiba, K. Saitoh, K. Takenaga, and S. Matsuo, “Analytical expression of average power-coupling coefficients for estimating intercore crosstalk in multicore fibers,” IEEE Photon. J. |

6. | K. Saitoh, M. Koshiba, K. Takenaga, and S. Matsuo, “Crosstalk and core density in uncoupled multicore fibers,” IEEE Photon. Technol. Lett. |

7. | H. Takara, A. Sano, T. Kobayashi, H. Kubota, H. Kawakami, A. Matsuura, Y. Miyamoto, Y. Abe, H. Ono, K. Shikama, Y. Goto, K. Tsujikawa, Y. Sasaki, I. Ishida, K. Takenaga, S. Matsuo, K. Saitoh, M. Koshiba, and T. Morioka, “1.01-Pb/s(12 SDM/222 WDM/456 Gb/s) crosstalk-managed transmission with 91.4-b/s/Hz aggregate spectral efficiency,” ECOC2012, paper Th.3.C.1 (2012). |

8. | V. A. J. M. Sleiffer, Y. Jung, V. Veljanovski, R. G. H. van Uden, M. Kuschnerov, H. Chen, B. Inan, L. G. Nielsen, Y. Sun, D. J. Richardson, S. U. Alam, F. Poletti, J. K. Sahu, A. Dhar, A. M. J. Koonen, B. Corbett, R. Winfield, A. D. Ellis, and H. de Waardt, “73.7 Tb/s (96 x 3 x 256-Gb/s) mode-division-multiplexed DP-16QAM transmission with inline MM-EDFA,” Opt. Express |

9. | E. Ip, N. Bai, Y. K. Huang, E. Mateo, F. Yaman, M. J. Li, S. Bickham, S. Ten, J. Liñares, C. Montero, V. Moreno, X. Prieto, V. Tse, K. M. Chung, A. Lau, H. Y. Tam, C. Lu, Y. Luo, G. D. Peng, and G. Li, “88×3×112-Gb/s WDM transmission over 50 km of three-mode fiber with inline few-mode fiber amplifier,” ECOC2011, paper Th.13.C.2 (2011). |

10. | N. Hanzawa, K. Saitoh, T. Sakamoto, T. Matsui, S. Tomita, and M. Koshiba, “Asymmetric parallel waveguide with mode conversion for mode and wavelength division multiplexing transmission,” OFC2012, paper OTU1I.4 (2012). |

11. | R. Ryf, R. Essiambre, A. H. Gnauck, S. Randel, M. A. Mestre, C. Schmidt, P. J. Winzer, R. Delbue, P. Pupalaikis, A. Sureka, T. Hayashi, T. Taru, and T. Sasaki, “Space-division multiplexed transmission over 4200-km 3-Core microstructured fiber,” OFC2012, paper PDP5C.2 (2012). |

12. | A. Li, X. Chen, A. Al Amin, and W. Shieh, “Fused fiber mode couplers for few-mode transmission,” IEEE Photon. Technol. Lett. |

13. | R. Ryf, N. K. Fontaine, and R. Essiambre, “Spot-based mode couplers for mode-multiplexed transmission in few-mode fiber,” IEEE Photon. Technol. Lett. |

14. | T. Sakamoto, T. Mori, T. Yamamoto, and S. Tomita, “Differential mode delay managed transmission line for WDM-MIMO system using multi-step Index fiber,” J. Lightwave Technol. |

15. | T. Mori, T. Sakamoto, M. Wada, T. Yamamoto, and F. Yamamoto, “Low DMD four LP mode transmission fiber for wide-band WDM-MIMO system,” OFC2013, paper OTh3K.1 (2013). |

16. | R. Ryf, M. A. Mestre, A. H. Gnauck, S. Randel, C. Schmidt, R.-J. Essiambre, P. J. Winzer, R. Delbue, P. Pupalaikis, A. Sureka, Y. Sun, X. Jiang, D. W. Peckham, A. McCurdy, and R. Lingle, Jr., “Low-loss mode coupler for mode-multiplexed transmission in few-mode fiber,” OFC2012, paper PDP5B.5 (2012). |

17. | R. Ryf, S. Randel, N. K. Fontaine, M. Montoliu, E. Burrows, S. Corteselli, S. Chandrasekhar, A. H. Gnauck, C. Xie, R.-J. Essiambre, P. J. Winzer, R. Delbue, P. Pupalaikis, A. Sureka, Y. Sun, L. Gr¨uner-Nielsen, R. V. Jensen, and R. Lingle, Jr., “32-bit/s/Hz spectral efficiency WDM transmission over 177-km few-mode fiber,” OFC2013, paper PDP5A.1 (2013). |

18. | N. K. Fontaine, R. Ryf, B. Guan, and D. T. Neilson, “Wavelength blocker for few-mode-fiber space-division multiplexed systems,” OFC2013, paper OTh1B.1 (2013). |

19. | T. Uematsu, K. Saitoh, N. Hanzawa, T. Sakamoto, T. Matsui, K. Tsujikawa, and M. Koshiba, “Low-loss and broadband PLC-type mode (de)multiplexer for mode-division multiplexing transmission,” OFC2013, paper OTh1B.5 (2013). |

20. | M. Oguma, T. Kitoh, A. Mori, and H. Takahashi, “Ultrawide-passband tandem MZI-synchronized AWG and group delay ripple balancing out technique,” ECOC2010, paper We8.E .2 (2010). |

21. | H. Kubota, M. Oguma, and H. Takara, “Three-mode multi/demultiplexing experiment using PLC mode multiplexer and its application to 2+1 mode bi-directional optical communication,” IEICE Electron. Express |

22. | W. V. Sorin, B. Y. Kim, and H. J. Shaw, “Highly selective evanescent modal filter for two-mode optical fibers,” Opt. Lett. |

**OCIS Codes**

(060.2270) Fiber optics and optical communications : Fiber characterization

(060.2400) Fiber optics and optical communications : Fiber properties

**ToC Category:**

Fiber Optics and Optical Communications

**History**

Original Manuscript: September 17, 2013

Revised Manuscript: October 15, 2013

Manuscript Accepted: October 15, 2013

Published: October 21, 2013

**Citation**

Nobutomo Hanzawa, Kuimasa Saitoh, Taiji Sakamoto, Takashi Matsui, Kyozo Tsujikawa, Masanori Koshiba, and Fumihiko Yamamoto, "Two-mode PLC-based mode multi/demultiplexer for mode and wavelength division multiplexed transmission," Opt. Express **21**, 25752-25760 (2013)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-22-25752

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### References

- D. Qian, M. F. Huang, E. Ip, Y. K. Huang, Y. Shao, J. Hu, and T. Wang, “101.7-Tb/s (370x294-Gb/s) PDM-128QAM-OFDM transmission over 3x55-km SSMF using pilot-based phase noise mitigation,” OFC2011, paper PDPB5 (2011).
- T. Morioka, Y. Awaji, R. Ryf, P. Winzer, D. Richardson, and F. Poletti, “Enhancing optical communications with brand new fibers,” IEEE Commun. Mag.50(2), s31–s42 (2012). [CrossRef]
- K. Imamura, Y. Tsuchida, K. Mukasa, R. Sugizaki, K. Saitoh, and M. Koshiba, “Investigation on multi-core fibers with large Aeff and low micro bending loss,” Opt. Express19(11), 10595–10603 (2011). [CrossRef] [PubMed]
- T. Hayashi, T. Taru, O. Shimakawa, T. Sasaki, and E. Sasaoka, “Characterization of crosstalk in ultra-low-crosstalk multi-core fiber,” J. Lightwave Technol.30(4), 583–589 (2012). [CrossRef]
- M. Koshiba, K. Saitoh, K. Takenaga, and S. Matsuo, “Analytical expression of average power-coupling coefficients for estimating intercore crosstalk in multicore fibers,” IEEE Photon. J.4(5), 1987–1995 (2012). [CrossRef]
- K. Saitoh, M. Koshiba, K. Takenaga, and S. Matsuo, “Crosstalk and core density in uncoupled multicore fibers,” IEEE Photon. Technol. Lett.24(21), 1898–1901 (2012). [CrossRef]
- H. Takara, A. Sano, T. Kobayashi, H. Kubota, H. Kawakami, A. Matsuura, Y. Miyamoto, Y. Abe, H. Ono, K. Shikama, Y. Goto, K. Tsujikawa, Y. Sasaki, I. Ishida, K. Takenaga, S. Matsuo, K. Saitoh, M. Koshiba, and T. Morioka, “1.01-Pb/s(12 SDM/222 WDM/456 Gb/s) crosstalk-managed transmission with 91.4-b/s/Hz aggregate spectral efficiency,” ECOC2012, paper Th.3.C.1 (2012).
- V. A. J. M. Sleiffer, Y. Jung, V. Veljanovski, R. G. H. van Uden, M. Kuschnerov, H. Chen, B. Inan, L. G. Nielsen, Y. Sun, D. J. Richardson, S. U. Alam, F. Poletti, J. K. Sahu, A. Dhar, A. M. J. Koonen, B. Corbett, R. Winfield, A. D. Ellis, and H. de Waardt, “73.7 Tb/s (96 x 3 x 256-Gb/s) mode-division-multiplexed DP-16QAM transmission with inline MM-EDFA,” Opt. Express20(26), B428–B438 (2012). [CrossRef] [PubMed]
- E. Ip, N. Bai, Y. K. Huang, E. Mateo, F. Yaman, M. J. Li, S. Bickham, S. Ten, J. Liñares, C. Montero, V. Moreno, X. Prieto, V. Tse, K. M. Chung, A. Lau, H. Y. Tam, C. Lu, Y. Luo, G. D. Peng, and G. Li, “88×3×112-Gb/s WDM transmission over 50 km of three-mode fiber with inline few-mode fiber amplifier,” ECOC2011, paper Th.13.C.2 (2011).
- N. Hanzawa, K. Saitoh, T. Sakamoto, T. Matsui, S. Tomita, and M. Koshiba, “Asymmetric parallel waveguide with mode conversion for mode and wavelength division multiplexing transmission,” OFC2012, paper OTU1I.4 (2012).
- R. Ryf, R. Essiambre, A. H. Gnauck, S. Randel, M. A. Mestre, C. Schmidt, P. J. Winzer, R. Delbue, P. Pupalaikis, A. Sureka, T. Hayashi, T. Taru, and T. Sasaki, “Space-division multiplexed transmission over 4200-km 3-Core microstructured fiber,” OFC2012, paper PDP5C.2 (2012).
- A. Li, X. Chen, A. Al Amin, and W. Shieh, “Fused fiber mode couplers for few-mode transmission,” IEEE Photon. Technol. Lett.24(21), 1953–1956 (2012). [CrossRef]
- R. Ryf, N. K. Fontaine, and R. Essiambre, “Spot-based mode couplers for mode-multiplexed transmission in few-mode fiber,” IEEE Photon. Technol. Lett.24(21), 1973–1976 (2012). [CrossRef]
- T. Sakamoto, T. Mori, T. Yamamoto, and S. Tomita, “Differential mode delay managed transmission line for WDM-MIMO system using multi-step Index fiber,” J. Lightwave Technol.30(17), 2783–2787 (2012). [CrossRef]
- T. Mori, T. Sakamoto, M. Wada, T. Yamamoto, and F. Yamamoto, “Low DMD four LP mode transmission fiber for wide-band WDM-MIMO system,” OFC2013, paper OTh3K.1 (2013).
- R. Ryf, M. A. Mestre, A. H. Gnauck, S. Randel, C. Schmidt, R.-J. Essiambre, P. J. Winzer, R. Delbue, P. Pupalaikis, A. Sureka, Y. Sun, X. Jiang, D. W. Peckham, A. McCurdy, and R. Lingle, Jr., “Low-loss mode coupler for mode-multiplexed transmission in few-mode fiber,” OFC2012, paper PDP5B.5 (2012).
- R. Ryf, S. Randel, N. K. Fontaine, M. Montoliu, E. Burrows, S. Corteselli, S. Chandrasekhar, A. H. Gnauck, C. Xie, R.-J. Essiambre, P. J. Winzer, R. Delbue, P. Pupalaikis, A. Sureka, Y. Sun, L. Gr¨uner-Nielsen, R. V. Jensen, and R. Lingle, Jr., “32-bit/s/Hz spectral efficiency WDM transmission over 177-km few-mode fiber,” OFC2013, paper PDP5A.1 (2013).
- N. K. Fontaine, R. Ryf, B. Guan, and D. T. Neilson, “Wavelength blocker for few-mode-fiber space-division multiplexed systems,” OFC2013, paper OTh1B.1 (2013).
- T. Uematsu, K. Saitoh, N. Hanzawa, T. Sakamoto, T. Matsui, K. Tsujikawa, and M. Koshiba, “Low-loss and broadband PLC-type mode (de)multiplexer for mode-division multiplexing transmission,” OFC2013, paper OTh1B.5 (2013).
- M. Oguma, T. Kitoh, A. Mori, and H. Takahashi, “Ultrawide-passband tandem MZI-synchronized AWG and group delay ripple balancing out technique,” ECOC2010, paper We8.E .2 (2010).
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